A construction floor, a roof, a wall, and a construction wall plate of an outer wall in a concrete-made structure and a floor made of steel framed reinforced concrete have been conventionally fabricated by forming a certain temporary form in a construction site, arranging reinforcing steels, if necessary, and introducing concrete into the form and hardening concrete. In place of the construction employing a form in a construction site, there have been widely used a construction method of preparing a concrete-made panel which has been in advance made in a factory, that is, a so-called pre-cast plate, and carrying the pre-cast plate to a construction site, and attaching the pre-cast plate to a structure, because the construction method makes it possible to enhance workability and shorten a construction period.
In the conventional construction methods as mentioned above, the method including the steps of constructing a temporary form in a construction site and introducing concrete into the form takes much time and effort in constructing a temporary form in a construction site, introducing concrete into the form, and curing the concrete. Hence, the construction cost is increased, and there is a limitation in shortening the construction period. In addition, since a large amount of concrete is used, the resulting structure weighs much. In the case of a skyscraper, there would arise a limitation that larger beams have to be used in underlying floors.
With respect to an increase in weight due to employing concrete, it would be possible to used light-weight concrete in place of ordinary concrete to thereby lighten a structure. However, since the conventional light-weight concrete lacks strength, a construction has be made thicker in order to compensate for the lack of strength, resulting in additional limitations in designing a construction.
On the other hand, the method of in advance fabricating concrete-made panels in a factory for enhancing workability, the most important point is to make the concrete-made panels light-weight, as much as possible, in order to enhance transfer efficiency from a factory to a construction site and also improve handling efficiency. The applicant of the present invention has already suggested a light-weighted concrete-made panel in Japanese Patent Application No. 5-257706, which was published as Japanese Unexamined Patent Publication No. 7-90972.
The concrete-made panel disclosed in the Publication is comprised of a pair of non-flammable boards vertically spaced away from each other, a corrugated steel plate sandwiched between the pair of the non-flammable boards, an outer frame securing to the corrugated steel plate at its periphery for sealing, and hard foaming resin filled in the outer frame. The concrete-made panel is ensured to have a sufficient strength since the corrugated steel plate has a sufficient strength, and to be more light-weight in comparison with conventional light-weight concrete.
The corrugated steel plate is arranged in such a way that outer surfaces of mountain (peak) and valley (trough) portions thereof are in abutment with surfaces of the non-flammable boards, and thus a restraint force does scarcely exert between the corrugated steel plate and the non-flammable boards in a direction of corrugation pitch of the corrugated steel plate. In other words, the upper non-flammable board is supported by the outer frame so that the non-flammable boards are mounted on the mountain or peak portions of the corrugated steel plate, and that the lower non-flammable board makes contact with the valley or trough portions of the corrugated steel plate. Hence, the corrugated steel plate provides compensation against a vertical compression force, and, the corrugated steel plate provides a little support against an external force acting on the non-flammable board in a direction of the corrugation pitch.
As mentioned above, by employing the corrugated steel plate, a construction can be made light-weight. However, since a restraint force is small in a direction of the corrugation pitch between the non-flammable boards and the corrugated steel plate, an extra retaining structure has to be added when the non-flammable boards and the corrugated steel plate are connected to each other through the outer frame.
It is of course possible to integrally form a concrete-made panel including a corrugated steel plate therein, an outer frame, and an upper and lower non-flammable boards through concrete. To this end, a frame acting as a container is used in combination with a core. Employing a core, there is formed a mold having a cavity into which a corrugated steel plate is to be inserted.
However, even if such a mold is used, after a hollow concrete-made panel has been fabricated, a corrugated steel plate is inserted into the concrete-made panel. Thus, mountain or peak and valley trough portions of the corrugated steel plate simply make abutment with an inner wall of the cavity of the concrete-made panel. Accordingly, similarly to the above, sufficient strength can be obtained against compression, however the restraint between the corrugated steel plate and the concrete-made panel in a direction of the corrugation pitch is left small.
The concrete-made panel having a corrugated steel plate therein is preferable with respect to making the panel light-weight, there remains a unsolved problems about the connection between a cover material of concrete and a corrugated steel plate.
It is an object of the present invention to provide a concrete-made panel which is light-weight, has a high strength, and is superior in heat and sound insulation, and a method of fabricating the same.